A Calverton man was stabbed while walking to his car in the Mattituck Plaza shopping center after leaving a nearby convenience store Monday night, Southold Town Police said.

The suspect demanded money from the victim and when the man did not comply, he cut him once in the upper torso, beneath his arm, police said. The incident occurred about 11:30 p.m.

The victim was found by Riverhead police on the Main Road in Aquebogue, according to Southold Town Police Chief Martin Flatley. The man, who speaks Spanish, ran into a language barrier when he initially tried to contact police from his cellphone, but it wasn’t immediately clear if the call went to Southold, Riverhead or the Southampton Town Police. He was taken to Peconic Bay Medical Center for treatment of his stab wound, Chief Flatley said.

Riverhead police conducted the initial investigation and traced the reported attack back to Mattituck. It does not appear that the man knew the alleged assailant, Chief Flatley said.

There were witnesses, who shouted at the suspect before he fled, but police said the witnesses did not come forward. Southold Town Police are asking anyone with information about the attack to call the detective division at (631) 765-2600.

Business owners and customers in the Plaza said they were surprised by the report of a robbery.

“Mattituck is pretty quiet,” said Bill Goff, manager of the Waldbaum’s in the shopping center. “I hope they catch [the suspect].”

Mr. Goff said the parking lot lights remain on at night, but said his employees leave the store around 9 p.m., and that the two night shift employees were inside the store at the time of the alleged robbery.

A manager at the 7-Eleven store near where the incident occurred said he didn’t know about what happened, but had been called in the investigation.

Some expressed concerns that the area may not be as safe as it once was.

“Over the years it has gotten worse,” said local resident Donna Burden. “There have been more incidents … We live in a small town, it shouldn’t be happening.” She said she wanted to see more police patrolling in the area.

Ms. Burden, who has lived on the North Fork for nearly two decades, said she used to leave her doors unlocked at night; now she locks them when she is alone in the house.